by Ron Joseph
Removing Paint from a Tin Roof
Q. I have a 100 year old tin roof that we have been preparing to paint. The
roof has been power washed several times and scraped but the old paint continues
to flake and break off in brital chunks. Have any suggestions?
A. Other methods include abrasive blasting with sand or grit, but this will
result in dust and abrasives contaminating everything in sight, so unless a
contractor can contain the dust, it is not an appropriate method.
You can power wash with abrasives added to the water. Sodium bicarbonate (baking
soda) is used at some industrial facilities. The advantage of this is that the
water and sodium bicarb are not hazardous and can be sent down the storm water
drain, provided that you filter out the paint particles and paint chips. Also
you are unikely to generate much dust.
Chemical paint strippers include methylene chloride, NMP, hydrogen peroxide
based and other chemicals. Methylene chloride is considered a hazardous air
pollutant by the EPA and I would hate to see you use large quantities of this
material. The other chemicals are available from specialty suppliers. To the
best of my knowledge, but I do not know this to be fact, the NMP and peroxide
strippers are not hazardous, but once the softened, dissolved paint is incorporated
in the stripper you might have a problem disposing of the waste.
Based on the above, your best bet might be power washing or water blasting with
solidum bicarb. A contractor should do this for you.